# Vortessence Memory Forensics
#
# Copyright 2007-2015 Volatility Foundation
#
# Copyright 2015 Bern University of Applied Sciences
#
# This program is  free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import re

class FormatSpec(object):
    def __init__(self, string = '', **kwargs):
        self.fill = ''
        self.align = ''
        self.sign = ''
        self.altform = False
        self.minwidth = -1
        self.precision = -1
        self.formtype = ''

        if string != '':
            self.from_string(string)

        # Ensure we parse the remaining arguments after the string to that they override
        self.from_specs(**kwargs)

    def from_specs(self, fill = None, align = None, sign = None, altform = None, minwidth = None, precision = None, formtype = None):
        ## Allow setting individual elements using kwargs 
        if fill is not None:
            self.fill = fill
        if align is not None:
            self.align = align
        if sign is not None:
            self.sign = sign
        if altform is not None:
            self.altform = altform
        if minwidth is not None:
            self.minwidth = minwidth
        if precision is not None:
            self.precision = precision
        if formtype is not None:
            self.formtype = formtype

    def from_string(self, formatspec):
        # Format specifier regular expression
        regexp = "\A(.[<>=^]|[<>=^])?([-+ ]|\(\))?(#?)(0?)(\d*)(\.\d+)?(.)?\Z"

        match = re.search(regexp, formatspec)

        if match is None:
            raise ValueError("Invalid format specification: " + formatspec)

        if match.group(1):
            fillalign = match.group(1)
            if len(fillalign) > 1:
                self.fill = fillalign[0]
                self.align = fillalign[1]
            elif fillalign:
                self.align = fillalign

        if match.group(2):
            self.sign = match.group(2)
        if match.group(3):
            self.altform = len(match.group(3)) > 0
        if len(match.group(4)):
            if not self.fill:
                self.fill = "0"
                if not self.align:
                    self.align = "="
        if match.group(5):
            self.minwidth = int(match.group(5))
        if match.group(6):
            self.precision = int(match.group(6)[1:])
        if match.group(7):
            self.formtype = match.group(7)

    def to_string(self):
        formatspec = ""
        if self.align:
            formatspec = self.fill + self.align
        formatspec += self.sign
        if self.sign == '(':
            formatspec += ')'
        if self.altform:
            formatspec += '#'
        if self.minwidth >= 0:
            formatspec += str(self.minwidth)
        if self.precision >= 0:
            formatspec += '.' + str(self.precision)
        formatspec += self.formtype

        return formatspec

    def __str__(self):
        return self.to_string()
